Washington, July 13 (Reuters): Researchers have said they were starting to find clues left by cancer when it begins to spread, and hoped to develop them into tests that may save the lives of future patients.

They found several of the genetic and protein markers in the blood and tissue of patients whose cancer had killed them.

Some of those markers should serve as early tests for the spread, or metastasis, of cancer, they told a meeting of the American Association of Cancer Research. If caught early enough, cancer is highly curable.

“People don’t die because they got cancer. People die because they got cancer and we didn’t detect it at a point where we could do something about it,” Dr Andrew von Eschenbach, head of the National Cancer Institute, told a news conference. Metastasis is responsible for 90 per cent of cancer deaths, according to the American Cancer Society.

Joan Massague, a Howard Hughes Medical Institute researcher at New York’s Memorial Sloan-Kettering Cancer Center, and colleagues have been making painstaking search for the products used by cancer cells to spread. The cells must first travel around the body, find the bone, brain or other tissue they will invade and then literally break in. Each process will require different genes and proteins.

The research team started with tissue samples taken from a patient who died of breast cancer, but Massague said they were making similar findings in samples from other breast cancer patients as well as those with prostate cancer and melanoma.

First, they inoculated them into specially bred mice — a standard first step in cancer research. The mice develop tumours made up of human cells, which can be studied.

They noted which genes were overactive in those tumours and then did a reverse test — genetically engineering normal cells with those genes and seeing if they metastasised in mice.